Effects of air in the system, Fluid capacity considerations, Frothing – MTS Model 286-20 Confining Pressure Intensifier User Manual
Page 26
286.20 Pressure Intensifier
26
Confining System Operation Considerations
Operation
Effects of Air In The System
The operating procedures provided in this section include instructions for
removing air from the pressurized parts of the system before pressurizing the
confining fluid.
A large volume of air can affect system response time, when operating in the
pressure control mode, or it can affect the expected relationship between pressure
and volumetric displacement, when operating in the displacement control mode,
especially when low pressures are involved.
Fluid Capacity Considerations
The CPI’s reservoir has sufficient capacity for normal operation with any MTS
triaxial cell. If the CPI is to be used with pressure vessels requiring greater
capacities, a separate container of confining fluid is usually used.
When a separate fluid storage container is used to increase reservoir capacity
during CPI operating procedures, the container is typically used as the source for
the volume of fluid required to fill the pressure vessel and the CPI’s reservoir is
used as the source for the CPI’s pressure intensifier. When used in this manner,
the CPI’s air-driven hydraulic pump is used to fill the pressure vessel, directly
from the storage container. When the pressure vessel must be emptied, fluid is
forced from the vessel by compressed air applied through the Air Direction
control, although the expelled fluid must first go through the CPI’s reservoir, then
to the external container via the Fluid Direction valve.
Frothing
Certain procedures which involve air flow into the bottom of the fluid reservoir,
such as
on page 42, can cause frothing of the fluid
in the reservoir.
Frothing can quickly cause fluid in the reservoir to overflow.
Always observe the reservoir while emptying the triaxial cell and take steps to
avoid overflow:
A. Open the reservoir fill valve one turn, or less.
B. Slow or shut off the flow of air before overflow occurs.